1) Field of the Invention
The invention relates to a device for separating a bodily fluid into fractions under centrifugal force, which device comprises a flexible container system, this container system comprising at least a first container for the fluid to be separated and a second container for a separated fraction, wherein the containers are mutually connected using a connecting conduit for a fluid. The invention also relates to a method for separating blood platelet concentrate into fractions under centrifugal force.
2) Description of the Prior Art
Human blood substantially comprises four components, i.e. blood plasma, blood platelets (thrombocytes), white blood cells (leukocytes) and red blood cells. The white blood cells and the blood platelets are together also referred to as buffy coat, and usually form about 1% of the blood. The red blood cells form about 45% of the blood, while the remaining part, i.e. about 54%, is formed by blood plasma. The demand for the different blood constituents in the purest possible form is considerable and continues to increase. Different methods are known from the prior art for producing blood products by separating the different constituents from each other. A known method for separating whole blood into different fractions such as red cells, blood platelets and plasma comprises of applying centrifugal force. In such a method a plastic container with a unit of whole blood of for instance between 400-550 ml is placed in a centrifuge. By applying centrifugal forces the components of the blood are separated from each other into layers, wherein the layer distribution is determined by the specific weight of the constituents of the blood. The container with the different layers is subsequently removed carefully from the centrifuge and placed in a pressing device with which the layers are pressed to different containers. Using this container system there is the possibility of separating blood during centrifuging thereof into the different blood constituents, wherein different blood constituents enter different containers. Using such a separation technology blood products, i.e. blood constituents, are obtained in a relatively pure form and in a satisfactory yield. The above described method can also be applied directly in the case of a blood donor, wherein blood is taken and then separated. The desired blood products are pressed and collected and the other constituents are returned directly to the donor. This method is known to the skilled person under the name apheresis. In order to increase the quality of the thus obtained blood products to the desired level, they have to be filtered in order to thereby reduce particularly the leukocyte content. Because of better clinical effects, blood products with a reduced content of leukocytes have a higher value, and therefore also a higher price. Particularly blood platelet concentrates obtained in accordance with the above method have too high a leukocyte content. An additional step is necessary in order to make a blood platelet concentrate from whole blood. For this purpose a number of blood platelet concentrates are generally combined and separately centrifuged once again so that at least part of the leukocytes are separated. After centrifuging, the blood platelet concentrate freed of leukocytes is pressed to a separate container via a conduit. After this step the blood platelet concentrate is then filtered once again in order to comply with the current standards for blood products, wherein the limit for low-leukocyte blood components is generally set at a leukocyte content lower than 1 million leukocytes per therapeutic unit. It is however generally known from the literature that contact of blood constituents with filter material of leukocyte filters has an adverse effect on the quality of the relevant blood constituents. Enzymes and cytokines can for instance thus be released from the leukocytes, which is undesirable. Part of the constituents is generally also lost because they remain behind in the filter. Blood platelets in particular are found to be very sensitive to such an additional filtration, among other reasons because of the high activation sensitivity. Other side-effects are described in the literature. In addition to the stated quality aspects of the blood platelets, another factor is that an additional processing step must be performed. The use of leukocyte filters moreover has a cost increasing effect.
NL 1006731 C2 describes a device for separating a bodily fluid into fractions under centrifugal force. The device comprises a flexible container system with containers which are mutually connected using connecting conduits. While a reasonable degree of separation can be achieved with the device described in NL 1006731 C2, this is not however at the desired level.
The present invention has for its object to provide a device and method for separating a bodily fluid, in particular blood platelet concentrate, into fractions under centrifugal force, wherein a high-quality blood product is obtained. The present invention has the particular object of providing a device and method for separating blood platelet concentrate into fractions under centrifugal force wherein a low-leukocyte blood platelet concentrate is obtained.